Apparatus for controlling refrigerant pressures in refrigeration and air condition systems



May 3, 1966 W. V. MAUER APPARATUS FOR CONTROLLING REFRIGERANT PRESSURE REFRIGERATION AND AIR CONDITION SYSTEMS Filed Aug. 21, 1964 SIN 2 Sheets-Sheet 1 20 77 72 war/2 2 36 1a E-\SUPPLY a0 1 a.

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INVENTOR.

WL'M'am 1 Newer May 3, 1966 w. v. MAUER 3,248,895

APPARATUS FOR CONTROLLING REFRIGERAN'I' PRESSURES IN REFRIGERATION AND AIR CONDITION SYSTEMS Filed Aug. 21, 1964 2 Sheets-Sheet 2 INVENTOR.

United States Patent Office I Patented May 3, 1966 3,248,895 APPARATUS FOR CONTROLLING REFRIGERANT PRESSURES 1N REFRIGERATION AND AIR CON- DITION SYSTEMS William v. Mailer, 40s W. 47th St., New York, NY. Filed Aug. 21, 1964, Ser. No. 391,115 17 Claims. (c1. 62157) This invention relates to control means for refrigerat1on and air conditioning systems having air-cooled condensers, evaporative condensers or atmospheric condensers.

Air cooled condensers are generally located out of doors or in such locations that they can be cooled by outdoor air. When the ambient air falls in temperature, such low condensing pressures result that there is insuificient refrigerant pressure to properly operate an expansion valve on the evaporator. This problem is well known and many expedients have been proposed for solving it. Due to their complexity, insufficient responsiveness to rapidly changing temperature, or other factors, the prior expedients proposed have not been wholly satisfactory and trouble-free.

The present invention is directed at overcoming these difiiculties and disadvantages of prior devices and controls directed at maintenance of operation of a refrig-' eration system at high efliciency at all ambient temperatures from sub-zero to more than 100 F., to which an air cooled condenser may be subjected.

An object of the invention is to keep a constant supply of liquid refrigerant under adequate pressure fed to a liquid receiver at all temperatures of ambient air used to cool a condenser.

Another object of the invention is to provide a cyclically-controlled liquid accumulator in a refrigeration system leading from the outlet of an air cooled condenser that will operate whenever the ambient temperature of the condenser drops below a predetermined point to supply liquid refrigerant to a receiver.

For further comprehension of the invention and of the objects and advantages thereof, reference will be had to the following description and accompanying drawings and to the appended claims in which the various novel features of the invention are more particularly set forth.

In the accompanying drawings forming a material part of this disclosure:

FIGS. 1, 2 and 3 are diagrams of refrigeration systems embodying the invention.

Referring first to FIG. 1, there is shown a refrigeration system S1 including a compressor which compresses a gaseous refrigerant and supplies the same via a high pressure pipe 12 to a condenser 14. The condenser is located in ambient air at an outdoor location, in unheated space or in a location where outdoor air can be supplied thereto for cooling the same. A fan 16 driven by a motor 18 may be use-d to drive or draw air across the condenser to cool the hot compressed gas therein. The cooled refrigerant in liquid form but still under high pressure is supplied to a liquid receiver 20 via outlet pipe 22 and a check valve 24. The refrigerant under pressure is fed from receiver 20 through pipe 26 to an evaporator 28 via an expansion valve 30. The evaporator may be located in a room, cabinet or other enclosed cooling chamber 32. The liquid refrigerant vaporized by heat drawn from chamber 32 is fed via the low pressure or suction line 34 to the intake of the compressor 10. To the extent described, the system is entirely conventional.

According to the present invention, a pressure responsive (P.R.) regulating valve 36 is connected in the pipe line 12 feeding compressed gaseous refrigerantvia supply line 12a to the condenser 14.

Valve 36 is a conventional spring-loaded adjustable valve selected to have an opening point which is adjustable within the range of saturated pressures correspond ing to temperatures in the range F. .to F., for the particular refrigerant being used. Valve 36 opens the instant that the compressor 10 begins to operate, maintaining a nearly constant pressure on the-inlet (upstream) side of the valve, and instantly providing full operating pressure through the equalizing line to the liquid refrigerant in the receiver 20. The outlet pressure will vary corresponding to the temperature and volume of air flowing through the air-cooled condenser 14. The total flow will vary slightly and cyclically as a small portion of the discharge gases are used to pressurize liquid accumulator 42. Valve 36 also acts as a check valve to prevent reverse flow of gases from the condenser 14 to the compressor 10 during off-cycle hot weather conditions. Valve 36 further functions to prevent oif-cycle flow of refrigerant from the evaporator 28 through the non-operating compressor to the condenser 14 when the temperature of the condenser falls below the temperature inside chamber 32 enclosing the evaporator.

An equalizing pipe line 38 is connected between the high pressure line 12 and the top of receiver 20 to apply pressure on the surface of liquid refrigerant R in the receiver.

Between the condenser 14 and the top of the receiver is connected liquid accumulator 42. The accumulator is downstream of check valve 24. A pipe v44 is connected between the bottom of the accumulator and the top of the receiver. A check valve 46 is provided in pipe 44.

A purge pipe line 52 is connected at one end between the downstream end of valve 36 and high pressure supply line 12a, and at the other end pipe 52 is connected to the top of accumulator 42. An electrically operated valve 55 is provided in pipe 52. This arrangement permits rapid purging of high pressure vapor in the accumulator 42 to the low pressure side of regulating valve 36 to equalize the pressure in the air-cooled condenser 14 and the liquid accumulator 42. The liquid refrigerant R is thereby permitted to flow by gravity from the bottom of the air-cooled condenser 14 through pipe 22 andcheck valve 24 into accumulator 42.

A pipe line 54 is connected at one end between the upstream end of pressure responsive regulating valve 36 and the discharge outlet of compressor 10. The other end of pipe 54 opens into the top of accumulator 42. An electrically operated stop valve 57 is provided in pipe 54. Both valves 55 and 57 are normally closed and are opened only when their solenoids 71, 73 are respectively energized.

Solenoids 71, 73 are connected to a timer 60 arranged so that when the timer is operated either valve 55 or valve 57 will be open while the other valve is closed. The timer includes a. timer switch 62 having a rotating contact arm 64 which alternately closes with arcuate shaped contact 65 and arcuate shaped contact 66. These contacts are of different lentghs so that the times when the valves 55, 57 are opened during the timing cycle are not equal. Solenoid 71 of valve 55 is connected to timer contact 65 and solenoid 73 of valve 57 is connected to timer. contact 66. The contact arm 64 of the timer is driven by a motor 75 connected via wire 78 to power supply 50 which energizes compressor 10. Contact arm 64 is also connected to power supply 50 via Wire 81.

A thermostatically controlled switch 76 is connected in wire 81 in series with contact arm 64 and power supply 50. A manually operable on-ofI switch 77 is connected trol circuit is not required, thermostatically controlled switch 76 opens on temperature rise to deactivate solenoids 71, 73 so that valves 55 and 57 are closed and the system operates in a conventional manner.

In operation of the system S1 under low ambient temperature conditions, the compressor 10 starts either upon the closing of switch 77 manually or in response to closing of temperature controlled switch 80 in the enclosure 32 connected to the compressor and calling for cooling. The refrigerant vapor in the evaporator 28 then flows through low pressure pipe 34 to the compressor 10 where the temperature and pressure of the refrigerant vapor are raised as the vapor is compressed. The high pressure, hot vapor flows from the compressor through pipe line 12 to pressure regulating valve 36 which remains closed until the pressure developed in line 12 exceeds the opening pressure set for valve 36. The high pressure, hot vapor in line 12, is applied through equalizing line 38 to the top of liquid receiver 20 and makes instantly available a supply of liquid refrigerant from the reactor 20 through line 26 to the expansion valve 30 or other metering device, at not less than a predetermined pressure. At the same time, check valve 46 is closed and prevents reverse flow of gases from the liquid receiver 20. Meanwhile pressure regulating valve 36 opens sufficiently to permit the flow of the high pressure, hot vapor through connecting line 12 and 12a to the air-cooled condenser 14. In the condenser, condensation of the refrigerant vapor takes place at a pressure that varies with the volume and temperature of the cooling air being passed across or through the air-cooled condenser.

Condensed, liquid refrigerant flows substantially by .w-geavity to the bottom of the condenser, through connect-- ing pipe line 22 and check valve 24 into the liquid accumulator 42. When the compressor motor starts, timing motor 75 starts. Power is applied through closed thermostatic switch 76, and arcuate contact 65 to energize solenoid 71 and open valve 55, thus equalizing the pressure above the liquid R in the accumulator 42 through purge line 52 with the pressure on the inlet side of condenser 14. This permits the accumulator to fill with liquid refrigerant R draining from the air-cooled condenser 14 by gravity. The arcuate contacts or segments 65, 66 are so dimensioned or adjusted that when accumulator 42 is filled with liquid refrigerant, timer arm 64 will have moved off contact 65 breaking the circuit to solenoid 71 and closing valve 55. At the same time the circuit through contact 66 will be closed and solenoid 73 will be energized to open valve 57. This will instantly provide high pressure vapor from line 12 through line 54 to the top of the accumulator 42. The pressure will thereby be raised above the liquid refrigerant R in the accumulator and the liquid refrigerant will be forced under pressure through line 44 and check valve 46 into liquid receiver 20. The equalizing line 38 will have a fine bore of such size that the pressure supplied through line 38 to receiver 20 is less than the full pressure supplied to accumulator 42 by line 54. Timer contact 66 has such a dimension that when liquid accumulator 42 is emptied, arm 64 will have travelled around to the starting point of contact 65. Solenoid 73 will then be deenergized to close valve 57 and at the same time solenoid 71 will be energized to open valve 55. This will permit venting of high pressure vapor in accumulator 42 to equalize its pressure with that of the air-cooled condenser 14. The cycle is then continued and repeated automatically alternately filling, emptying and purging the accumulator 42.

The thermostatic switch 76 located in the air stream of condenser 14 is used to de-energize the solenoids 71,

73 whenever the ambient temperature exceeds a predetermined temperature to avoid needless operation of valves 55, 57 during normal and/ or high outdoor ambient temperatures.

By the arrangement described, driving pressure is maintained in the receiver via equalizing line 38 which has a small bore to provide a limited pressure drop. A constant supply of condensed refrigerant under sufficient pressure is thus supplied to the receiver at all times, and the evaporator 28 and expansion valve 30 can operate efficiently regardless of the outside ambient temperature.

While an air-cooled condenser has been described in the present system, it should be understood that the system can be used effectively to solve operational dificulties occurring when other types of condensers such as evaporative and atmospheric condensers are used at low temperatures. In such other condensers when ambient Wetbulb and/or dry-bulb temperatures drop below predetermined conditions low liquid line pressures are developed; and when outdoor temperatures drop below the water freezing point, the evaporative type of condenser operates dry, so that operation becomes similar to that of an aircooled condenser subject to the same operational difiiculties which are controllable by the system described.

A magnet stop valve 36' may be connected in parallel with the pressure responsive valve 36 to permit by-passing of said pressure responsive valve 36 when high outdoor ambient temperatures obviate the need for valve 36. This by-pass valve 36' would be operated by the engagement of a contact 7611 by thermostat arm 76b when the temperature of the ambient air is high and above the designed temperature of the system. The by-pass valve when opened renders the pressure responsive valve 36, valve and 57 inoperative.

The contact 76a of the thermostat 76 is connected by wire 78' to one side of solenoid 36a of by-pass valve 36', the other side of which is grounded. In this manner, the working life of the pressure responsive valve 36 is extended and the operating efficiency of the system'is increased.

In FIG. 2, there is shown a refrigeration system S2 which is similar to system S1 of FIG. 1 and corresponding parts are identically numbered. System S2 has two liquid accumulators 42a, 4212 with liquid refrigerant R 'or R" in the respective accumulators. Each accumulator has its own check valve 46a or 46b in liquid pipe line 44a or 44b feeding receiver 20 via common line 44. Valve 55a in purge line 52a and valve 57a in pressure pipe line 54:: open alternately when their solenoids 71a, 7311 are energized at timer 60. Valve 55b in purge line 52b and valve 57b in pipe line 54b also open alternately. Since both solenoids 71b, 73a are connected together to timer contact 65, and since both solenoids 71a, 73b are connected together to timer contact 66 both valves 55]), 57a open together while valves 55a, 57b are closed and both valves 55b, 57a open together while valves 55a, 57b are closed.

Two check valves 24a, 241; are connected in pipe branches 22a, 22b of outlet line 22 of condenser 14. The branches-22a, 24b are connected to the accumulators respectively. The two accumulators 42a, 42b are connected in parallel and operate either together or alternately so that a constant supply of liquid refrigerant is supplied to the receiver by using two or more accumulators in parallel a smoother flow of liquid refrigerant is maintained to the receiver 20.

In FIG. 3 is shown a refrigeration control system S3 in which parts corresponding to those of systems S1 and S2 are identically numbered. In system S3, the timer is omitted and instead a float controlled switch 9%) is provided in the liquid accumulator 42'. This switch is operated by a float whose arm 91 is operatively connected to switch arm 93. The switch arm 93 has one position at contact 92 when the accumulator is filled with liquid R and another position at contact 94 when level of liquid R is low.

Solenoid 71' which operates to open valve 55' in purge line 52 is connected in circuit with a power supply 50 and contact 94. Solenoid which operates to open valve 57' in pressure line 54 is connected in circuit with the power supply and contact 92. Valves 55 and 57 operate alternately. Valve 55' is open When the level of liquid R in accumulator 42' is low while valve 57' is closed to purge the accumulator of vapor and permit fill:

ing the accumulator from the condenser 14. Valve 57' is open when the level of liquid R in the accumulator 42' is high while valve 57' is closed to admit vapor under pressure to the accumulator and drive liquid to the receiver 20. Thus system S3 operates like system S1, except that the float controlled switch 90 is employed instead of the timer 60.

The timer of system S2 can be replaced by float controlled switches in the accumulators in a manner similar to that shown in FIG. 3. If desired the float controlled switches used to operate the solenoid valves 55', 57' can be installed in the receiver 20 instead of in the accumulator.

A thermostat 76' in the inlet air stream to the condenser 14' opens on temperature rise and being connected in series with the common supply lines to solenoids 71' and 73' renders inoperative the valves 55' and 57' whenever the ambient air temperature at the condenser is such that operation of the valves are not needed.

While I have illustrated and described the preferred embodiments of my invention, it is to be understood that I do not limit myself to the precise constructions herein disclosed and that various changes and modifications may be made within the scope of the invention as defined in the appended claims.

What is claimed is:

1. A refrigeration system, comprising a vapor compressor, air-cooled condenser, liquid refrigerant accumulator, liquid refrigerant receiver and liquid refrigerant evaporation means, all the foregoing being connected by piping in a closed sem'es circuit, a pressure-responsive first valve in said circuit between the compressor and the condenser and operable when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressure-equalizing pipe line connected at one end to a point in said circuit between said compressor and said first valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said first valve and said condenser and connected at its other end to the accumulator for relieving vapor pressure therein to admit condensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at one end between the compressor and said first valve and connected at its other end to the accumulator for driving liquid refrigerant from the accumulator to the receiver, a second valve in the purge line, a third valve in the high pressure line, and means for opening and closing said second and third valves alternately to keep the receiver continuously supplied with liquid refrigerant at all ambient air temperatures to which the condenser is subjected.

2. A refrigeration system, comprising a vapor cornpressor, air-cooled condenser, liquid refrigerant accumulator, liquid refrigerant receiver and liquid refrigerant evaporation means, all the foregoing being connected by piping in a closed series circuit, a pressure-responsive first valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to said condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressureequalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said first valveand said condenser and connected at its other end to the accumulator for relieving vapor pressure therein to admit condensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at one end between fihe compressor and said first valve and connected at its other end to the accumulator for driving liquid refrigerant from the accumulator to the receiver, a second valve in the purge line, a third valve in the high pressure line, solenoid means associated with the respective second and third valves for opening the valves when the solenoid means are respectively energized, and means for energizting said second and third solenoid means alternately to keep the receiver continuously supplied with liquid refrigerant.

3. A refrigeration system, comprising a vapor compressor, air-cooled condenser, liquid refrigerant accumul'ator, liquid refrigerant receiver and liquid refrigerant evaporation means, all the foregoing being connected by piping in a closed series circuit, a pressure responsive first valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to said condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressure equalizing pipe line connected at one end to a point in said circuit between said compressor and sarid valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser and connected at its other end to the accumulator for relieving vapor pressure therein to admit condensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at one end between the compressor and said valve and connected at its other end to the accumulator for driving. liquid refrigerant from the accumulator to the receiver, a second valve in the purge line, a third valve in the high pressure line, solenoid means for opening the second and third valves respectively when their solenoid means is energized, thermostat means in circuit with the solenoid means for deactivating the same to keep the second and third valves closed at ambient temperatures above a predetermined temperature, and means for energizing the second and third solenoid means of the second and third valves alternately to keep the receiver continuously supplied with liquid refrigerant when the ambient air temperature to which the condenser is subjected falls below said predetermined temperature.

4. A refrigeration system, comprising a vapor compressor, air-cooled condenser, liquid refrigerant accumulator, liquid refrigerant receiver and liquid refrigerant evaporation means, all of the foregoing being connected by piping in a closed series circuit, a pressure responsive first valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to said condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressure equalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser and connected at its other end to the accumulator for relieving vapor pressure therein to admit c'ondensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at one end between the compressor and said valve and connected at its other end to the accumulator for driving liquid refrigerant from the accumulator to the receiver, a second valve in the purge line, a third valve in the high pressure line, solenoid means for opening the second and third valves respectively when their solenoid means is energized, thermostat means in circuit with the solenoid means for deactivating the same to keep the valves closed at ambient temperatures above a predetermined temperature, and ,a timer switch means having a plurality of switch contacts, said solenoid means for the second and third valves being connected to the switch contacts of the timer switch respectively for energizing the solenoid means of the respective second and third valves alternately to keep the receiver continuously supplied with liquid refrigerant.

5. A refrigeration system, comprising a vapor compressor, air-cooled condenser, liquid refrigerant accumulator, liquid refrigerant receiver and liquidrefrigerant evaporation means, all the foregoing being connected by.

piping in a closed series circuit, a pressure-responsive first valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to said condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressureequalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said first valve and said condenser and connected at its other end to the accumulator for relieving vapor pressure therein to admit condensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at oneend between the compressor and said first valve and connected at its other end to the accumulator for driving liquid refrigerant from the accumulator to the receiver, a first valve in the purge line, a second valve in the high pressure line, solenoid means for opening and closing the respective second and third valves alternately to keep the receiver continuously supplied with liquid refrigerant, and a thermostat located near the condenser and operatively connected to said solenoid means for deactivating the same to keep the valves closed at ambient temperatures above a pre determined temperature.

6. A refrigeration system, comprising a vapor com pressor, air-cooled condenser, liquid refrigerant accumulator, liquid refrigerant receiver and liquid refrigerant evaporation means, all the foregoing being connected by piping in a closed series circuit, a pressure-responsive first valve in said circuit between the compressor and condenser .for passing compressed refrigerant vapor to said condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressureequalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser and connected at its other end to the accumulator for relieving vapor pressure therein to admit condensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at one end between the compressor and said first valve and connected at its other end to the accumulator for driving liquid refrigerant from the accumulator to the receiver, a second valve in the purge line, a third valve in the high pressure line, solenoid means for opening the second and third valves respectively when their solenoid means is energized, and a motordriven timer switch having a plurality of switch contacts, said solenoid means for the second and third valves being connected to the switch contacts respectively for energizing the solenoid means of the second and third valves alternately to keep the receiver'continuously supplied with liquid refrigerant.

7. A refrigeration system, comprising a vapor compressor, air-cooled condenser, liquid refrigerant accumlh; lator, liquid refrigerant receiver and liquid refrigerant evaporation means, all the foregoing being connected by piping in a closed series circuit, a pressure-responsive first valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to said condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressure equalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser andconnected at its other end to the accumulator for relieving vapor pressure'therein to admit condensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at one end between the compressor and said valve and connected at its other end to the accumulator for driving liquid refrigerant from the accumulator to the receiver, a second valve in the purge line, a third valve in the high pressure line, solenoid means for opening the second and third valves respectively when their solenoid means is energized, and a float-controlled switch in said accumulator connected in circuit with the solenoid means for energizing the respective solenoid means for the second and third valves alternately to open and close the valves alternately so as to keep both the accumulator and receiver continuously supplied with liquid refrigerant.

8. A refrigeration system, comprising a vapor compressor, air-cooled condenser, liquid refrigerant accumulator, liquid refrigerant receiver and liquid refrigerant evaporation means, all the foregoing being connected by piping in a closed series circuit, a pressure-responsive first valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to said condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressureequalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser and connected at its other end to the accumulator for relieving vapor pressure therein to admit condensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at one end between the compressor and said valve and connected at its other end to the accumulator for driving liquid refrigerant from the accumulator to the receiver, a second valve in the purge line, a third valve in the high pressure line, means for opening the second and third valves respectively when their solenoid means is energized, and a float-controlled switch in circuit with the solenoid means for energizing the solenoid means of the second and third valves alternately to open and close the check valves alternately, said pressure-equalizing line having a bore narrower than that of the high pressure line so that less than full pressure developed by the compressor is applied to the receiver through the equalizing line while full pressure is applied to the accumulator through the high pressure line.

9. A refrigeration system, comprising a vapor compressor, air-cooled condenser, liquid refrigerant accumulator, liquid refrigerant receiver and liquid refrigerant evaporation means, all the foregoing being connected by piping in a closed series circuit, a pressure-responsive first valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to said condenser when pressure of vapor applied to said valve is above a predetermined medium pressure, a pressure-equalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser and connected at its other end to the accumulator for relieving vapor pressure therein to admit condensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at one end between the compressor and said valve and connected at its other end to the accumulator for driving liquid refrigerant from the accumulator to the receiver, a second valve in the purge line, a third valve in the high pressure line, solenoid means associated with the respective second and third valves for opening the same when the solenoid means are respectively energized, and means for energizing the solenoid means for the second and third valves alternately to keep the receiver continuously supplied with liquid refrigerant, said pressure-equalizing line having a bore narrower than that of the high pressure line so that less than full pressure developed by the compressor is applied to the receiver through the equalizing line while full pressure is applied to the accumulator through the high pressure line.

10. A refrigeration system, comprising a vapor compressor, air-cooled condenser, liquid refrigerant accumulator, liquid refrigerant receiver and liquid refrigerant evaporation means, all the foregoing being connected by piping in a closed series circuit, a pressure-responsive first valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to said condenser when pressure of vapor applied to said I valve'is above a predetermined minimum pressure, a pressure-equalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser and connected at its other end to the accumulator for relieving vapor pressure therein to admit condensed liquid refrigerant to the accumulator from the condenser, a high pressure line connected at one end between the compressor and said valve and connected at its other end to the accumulator for driving liquid refrigerant from the accumulator to the receiver, a normally closed second valve in the purge line, 21 normally closed third valve in the high pressure line, solenoid means for opening and closing the second and third valves alternately to keep the receiver continuously supplied with liquid refrigerant, and a thermostat located near the condenser and operatively connected to said solenoid means for deactivating the same to keep the second and third valves closed at ambient temperatures above a predetermined temperature, said pressure-equalizing line having a bore narrower than that of the high pressure line so that less than full pressure developed by the compressor is applied to the receiver through the equalizing line while full pressure is applied to the accumulator through the high pressure line.

11. A refrigeration system, comprising a vapor compressor, air-cooled condenser, a plurality of liquid accumulators having inlets connected together by common piping and having outlets connected together by common piping in a parallel arrangement, a liquid refrigerant receiver, and a liquid refrigerant evaporation means, all the foregoing being connected by pipe lines in a closed series' circuit, a pressure-responsive valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to the condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressure-equalizing pipe line connected at one end to a pointin said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from. the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser, said purge line having branches at its other end connected to the' accumulators respectively for relieving vapor pressure respectively for opening the same when thesolenoid means are energized, and means for energizing the solenoid means for the purge and high pressure line valves alternately to keep the receiver continuously supplied with liquid refrigerant.

12. A refrigeration system, comprising a vapor compressor, air-cooled condenser, a plurality of liquid accumulators having inlets connected together by common piping in a parallel arrangement, a liquid refrigerant receiver, and a liquid refrigerant evaporation means, all the foregoing being connected by pipe lines in a closed series circuit, a pressure-responsive valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to the condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressure-equalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser, said purge line having branches at its other end connected to the accumulators respectively for relieving vapor pressure therein, normally-closed valves in said purge line branches respectively, a high pressure line connected at one end between the compressor and said pressure-responsive valve, said high pressure line having branches at its other end connected to the accumulators respectively for driving liquid refrigerant from the accumulators to the receiver,

normally-closed valves in the branches respectively of the high pressure line, solenoid means associated with the respective purge and high pressure line valves respectively for opening the same when the solenoid means are energized, and means for energizing the solenoid means alternately to keep the receiver continuously supplied with liquid refrigerant, and a thermostat located near the condenser and connected in circuit with said solenoid means for deactivating the same to keep the valves closed when the air cooling of the condenser is above a predetermined temperature.

13. A. refrigeration system according to claim 12,

wherein said pressure-equalizing line has a bore narrower than that of the high pressure line so that less than full pressure developed by the compressor is applied to the receiver through the equalizing line while full pressure is applied to the accumulators through the equalizing line while full pressure is applied to the accumulators through the high pressure line.

14. A refrigeration system comprising a vapor compressor, air-cooled condenser, a plurality of liquid accumulators having inlets connected together by common piping and having outlets connected together by common piping in a parallel arrangement, a liquid refrigerant receiver, and a liquid refrigerant evaporation means, all the foregoing being connected by pipe lines in a closed series circuit, a pressure-responsive valve in said circuit between the compressor and condenser for passing compressed refrigerant vapor to the condenser when pressure of vapor applied to said valve is above a predetermined minimum pressure, a pressure-equalizing pipe line connected at one end to a point in said circuit between said compressor and said valve and at its other end to said receiver for driving liquid refrigerant from the receiver to said evaporation means, a purge line connected at one end between said valve and said condenser, said purge line having branches at its other end connected to the accumulators respectively for relieving vapor pressure therein, one-way normally closed valves in said branches respectively, a high-pressure line connected at one end between the compressor and said pressure responsive valve, said high pressure line having branches at its other end connected to the accumulators respectively for driving liquid refrigerant from the accumulators to the receiver, normally-closed valves in the branches respectively of the high pressure line, solennoid means associated with the respective purge and high pressure line check valves respectively for opening the same when the solenoid means are energized, and a motor-driven timer switch having a plurality of switch contacts, said solenoid means being connected to the switch contacts respectively for energizing the solenoid means of the purge and high pressure valves sequentially to keep the receiver continuously supplied with liquid refrigerant.

15. A refrigeration system according to claim 14, wherein said pressure equalizing line has a bore narrower than that of the high pressure line so that less than full pressure developed by the compressor is applied to the receiver through the equalizing line while full pressure is applied to the accumulators through the high pressure line.

16. A refrigeration system according to claim 14, further comprising a thermostat located near the condenser and connected in circuit with the solenoid means for deactivating the same to keep the first and second valves closed when the air cooling the condenser is above a predetermined temperature.

17. A refrigeration system according to claim 4 and solenoid operated by-pass valve means connected in parallel with the first pressure-responsive valve, said thermostat having a contact engaged by a thermostat arm at the time that the second and third valves are deactivated, said contact being connected to the solenoid-operated valve to effect the opening of the by-pass valve at this time.

References Cited by the Examiner UNITED STATES PATENTS 2,359,595 10/1944 Urban 62509 X 3,074,249 1/1963 Henderson 62174 X 3,082,610 3/ 1963 Marlo. 3,088,293 5/1963 Henderson 62-l74 X 3,145,543 8/1964 Miner.

MEYER PERLIN, Primary Examiner.

ROBERT A. OLEARY, Examiner.

L. L. KING, Assistant Examiner. 

1. A REFRIGERATION SYSTEM, COMPRISING A VAPOR COMPRESSOR, AIR-COOLED CONDENSER, LIQUID REFRIGERANT ACCUMULATOR, LIQUID REFRIGEARANT RECEIVER AND LIQUID REFRIGERANT EVAPORATION MEANS, ALL THE FOREGOING BEING CONNECTED BY PIPIN IN A CLOSE SERIES CIRCUIT, A PRESSURE-RESPONSIVE FIRST VALVE IN CIRCUIT BETWEEN THE COMPRESSOR AND THE CONDENSER AND OPERABLE WHEN PRESSURE OF VAPOR APPLIED TO SAID VALVE IS ABOVE A PREDETERMINED OF VAPOR APPLIED TO A PRESSURE-EQULIZING PIPE LINE CONNECTED AT ONE END TO A POINT IN SAID CIRCUIT BETWEEN SAID COMPRESSOR AND SAID FIRST VALVE AND AT ITS OTHER END TO SAID RECEIVER TO DRIVING LIQUID REFRIGERANT FROM THE RECEIVER TO SAID EVAPORATION MEANS, A PURGE LINE CONNECTED TO ONE END BETWEEN SAID FIRST VALVE AND SAID CONDENSER AND CONNECTED AT ITS OTHER END TO THE ACCUMULATOR FOR RELIEVING VAPOR PRESSURE THEREIN TO ADMIT CONDENSED LIQUID REFRIGERANT TO THE ACCUMULATOR FROM THE CONDENSER, A HIGH PRESSUE LINE CONNECTED AT ONE END BETWEEN THE COMPRESSOR AND SAID FIRST VALVE AND CONNECTED AT ITS OTHER END TO THE ACCUMULATOR FOR DRIVING LIQUID REFRIGERANT FROM THE ACCUMULATOR TO THE RECEIVER, A SECOND VALVE IN THE PURGE LINE, A THIRD VALVE IN THE HIGH PRESSURE LINE, AND MEANS FOR OPENING AND CLOSING SAID SECOND AND THIRD VALVES ALTERNATELY TO KEEP THE RECEIVER CONTINUOUSLY SUPPLIED WITH LIQUID REFRIGERANT AT ALL AMBIENT AIR TEMPERATURES TO WHICH THE CONDENSER IS SUBJECTED. 